Hey I'm new here. I have an Empire Comfort Systems DVD36FP30N direct vent gas fireplace that I am installing. I have to run a new line from my main NG line to the firebox through a very narrow crawl space and up through a hole in my wood floor, then into the bottom of the fireplace itself. I'm hiring a plumber to tie into the main NG line, which will be about 10 feet away. I talked to one plumber who said I had to use black steel pipe into the firebox itself, but I could use CSST from the main line to the black pipe. Is this correct? Can someone tell me what I need to use from the main gas supply, through the crawl space, up through the floor, and then into the firebox? I currently have the old black stem pipe and a stainless flexible line that came with the fireplace. What else do I need? Thank you so much in advance!